Ways to Keep Pesky Gypsy Moths Under Control

Ways to Keep Pesky Gypsy Moths Under Control

By MONA BAWGUS For The Press of Atlantic City (Published: July 6, 2007)

Question: There are multiple brownish moths flying around my oak trees. Are these gypsy moths and is there something I can do now to help my trees?

Answer:The large number of brown moths now seen flying around oak trees are male gypsy moths. There something you can do now to improve your situation next year.

If you take a look at your oak trees now, you may notice dead caterpillars or larvae lined up vertically, hanging upside down mainly around the bottom of the trunk. The bodies may also be moist and ooze dark fluid. That’s because Mother nature is taking a role in helping to combat the gypsy moth.

In past years along the Eastern states, collapses in the gypsy moth population have been due in part to a fungus, Entomophaga maimaiga. This fungus is a native of Japan and a natural enemy of the gypsy moth caterpillar. The fungus was collected in Japan and deliberately released in Boston in 1910. The following years showed little effect of the fungus in controlling the caterpillars.

However, in 1989, during a particularly wet spring and a high gypsy moth outbreak, larval populations collapsing were again noted. An examination of the dead carcasses revealed the presence of the spores of the fungus. It is believed the 1910 fungus was back as a stronger, more virulent evolution of the original fungus.

It is difficult to predict how the fungus acts in future years, but usually it is more prevalent in wetter years. Even with this good news, natural predators do not totally eradicate their hosts, so gypsy moths will always be present. To help reduce future infestations, some work on your part can be helpful.

Adult Gypsy Moths begin to appear in late June early July. Right now the moths are mating. The male moths are the ones seen flying around searching for a female. The females are white with black markings and straight threadlike black antennae. They are only found resting on the trunk as they are unable to fly.

Below the female you will see the eggs being deposited. Egg masses can be found in several locations: around loose bark, under branches, around the foundation of your home, on bird feeders, lawn ornaments and wood piles. After locating the casings, scrape them into a container of warm soapy water or a container that you can burn. Each egg mass destroyed will eliminate 400 to 1000 caterpillars.


Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Extension, 6260 Old Harding Highway, Mays Landing, N.J. 08330. E-mail: bawgus_mona@aclink.org